When to Test FOr Ovulation?

Karen • Can't wait to meet my Baby girl
I am Currently waiting for my Opk to arrive in the mail . When do you start to test for Ovulation? Imediately after Af or a few days after ? I have a 27 day cycle and Glow says i Ovulate a week after my Af is over. Also how often do you BD after you get a Positive Opk? I dont get to BD very often we both work a lot .